John Deere H oil pump

[steveks5]

I am restoring a 1940 John Deere H. My oil pressure seems low. About 12 pounds at full throttle. I was using 10w40 new oil. changed all oil when I got this tractor home. Oil pressure turned up as high as possible. Hoping to not pull the pump. Need some help please.

 

[tim s]

Check your gauge with another one I keep a standard low pressure gauge on a grease gun hoes to check engine oil pressure, if that proves out you may have worn bearings letting too much oil bay pass..

 

[Mark-Ia]

That's all it is supposed to have at full throttle.

 

[Mike M]

Does it stay at 12 or drop off to nothing at idle ?

I have seen a lot of H's with the oil filter can crushed which will let oil by pass and also seen more than not with loose rod and main bearings. Seldom have a bad oil pump.

 

[dan_41jdh]

As Mark-Ia indicated, that's all they're supposed to have. Oil pressure specifications for the model "H" are 10-15 PSI. Those old tractors didn't need much oil pressure, but there did need to be oil flow.

How many old-timers on this forum remember the old in-line 6 cylinder, 216 cubic inch Chevy engines that didn't have pressure lubrication to the rods, but depended on a "dip" system using the little catch cups on the rod caps that caught an oil spray into a series of curved troughs that conformed to the swing of the rod journal? No oil pressure to those rods, but there were sure a bunch of those engines made over the 25 years or so of production, and they worked just fine.

Regardless, the suggestion that Tim made is always good practice - you really need to check your oil pressure gauge against a known good gauge.

 

[steveks5]

Oil pressure comes down to 3 to 4 pounds at idle. Guess I am just trying to be lazy and not take the motor down any further than I have to. Thank you very much for the help.

 

[Richard G.]

Dan, I have a 51 Chevy pickup with that system. I also have a 17 Model T that the rods just grab a little oil as they go around. I call them both the splash and hope oiling system.
The 51 does have pipes that squirt oil at the rods as they dip in the trough.
Richard in NW SC

 

[Richard G.]

I run Rotella 15-40 in everything here. My H holds medium to high on the gauge which is about 7 to 15 pounds.
Richard in NW SC

 

[Paul from MI]

All of the old letter series 2 cylinders carried 10-15 psi oil pressure, so your oil pressure at full throttle is normal. But of more concern to me is the drop off to 3-4 psi at idle. The oil pump normally has so much more capacity than the engine needs that the by-pass valve is constantly dumping excess oil back into the crankcase. When the engine is slowed to an idle, the by-pass valve closes and stops dumping excess oil. So the pressure doesn't drop very much. None of my tractors will drop below the "M" mark on the gage, which is 10 psi, at an idle speed. So as others have said, you need to look into what is causing the drop at idle, especially if you are going to use the tractor. Could be loose engine bearings, or a filter housing distorted from overtightening, or even a cracked or broken oil line..